The control of internal combustion engines is configured in particular with a view to reducing the emission of toxic substances and optimizing the composition of the exhaust gases. Transient processes such as acceleration processes are, in this regard, critical operating states since they are responsible for brief deviations from the ideal mixture composition. Very rapid changes in the air mass supplied to the internal combustion engine have particularly negative effects on the mixture composition when the internal combustion engine is cold.
In order to optimize the composition of the exhaust gases during transient processes various approaches have been proposed. Thus, it is known, for example from U.S. Pat. No. 5,095,874, to adjust the fuel supply to the internal combustion engine in dependence upon the activation of the accelerator pedal. The air supply is then controlled in a way which optimizes the mixture composition on the basis of the quantity of fuel pregiven by the driver taking into account a wall film model, as may be required.
The entire right, title and interest to the present application and to U.S. patent application Ser. No. 08/378,020, filed Jan. 25, 1995, are assigned to the same assignee, namely, Robert Bosch GmbH of Stuttgart, Germany. U.S. patent application Ser. No. 08/378,020 discloses that the maximum rate of change of the air mass or air quantity is limited in the warm-up phase of the internal combustion engine in order to reduce the emission of toxic substances within the scope of an electronic control of the air supply to the engine in dependence upon the driver command.
The objective of all known proposals is to limit the rate of change in the air mass per time unit or to optimize the air/fuel system dynamically. However, if a given change in the driver command is to be realized, a corresponding change in the air supply must always be realized, if only with a limited rate of change.
U.S. Pat. No. 4,351,297 discloses that the ignition angle of the internal combustion engine is changed in the retard direction in order to heat up the catalytic converter more rapidly when the internal combustion engine is cold.